Installing fasteners require it to perform their functions according to the design and engineering structure. However, there are instances when the fasteners fail unexpectedly. The most common cause is hydrogen embrittlement.
Hydrogen embrittlement occurs when hydrogen enters a metal and makes it more brittle. This phenomenon affects high-strength steels and some alloys. This results in reduced ductility, lower fracture resistance, and a higher risk of cracking under stress.
Hydrogen embrittlement and stress corrosion cracking often occur without visible warning signs. Understanding embrittlement, such as the permanent loss of ductility due to atomic hydrogen, is the first step toward securing your supply chain.
This guide highlights the significance of utilizing hydrogen embrittlement fasteners and their uses. It also discusses ways to avoid hydrogen embrittlement and cracking.
How Does Hydrogen Embrittlement and Stress Corrosion Cracking Happen?
Hydrogen embrittlement happens when steel is exposed to an acid bath or a metal coating. Hydrogen atoms penetrate the steel structure in this case. Once stress is applied to steel, hydrogen atoms migrate to grain boundaries in the structure of steel.
To identify the cause of a failure, engineers examine the hydrogen embrittlement fracture surface. Under a scanning electron microscope, this surface typically shows intergranular separation.
Caustic embrittlement affects equipment in high-pH environments, such as boilers. This is why hydrogen-specific damage is the primary concern for high-tensile fasteners in automotive applications.
How to Prevent Hydrogen Embrittlement?
Hydrogen embrittlement fasteners manufacturers must implement strict thermal protocols. The most critical step is de-embrittlement, commonly known as hydrogen baking.
What is De-embrittlement?
De-embrittlement is a heat-treatment process used to remove or reduce hydrogen embrittlement in metal parts. This process is conducted after electroplating or other processes that introduce hydrogen into steel.
In practice, the part is baked at about 200 to 220 °C for a period of time so that trapped hydrogen can diffuse out of the metal. This lowers the risk of cracking or sudden failure.
Quality Assurance and Standards
For critical hydrogen embrittlement fastener uses, such as engine mounts or suspension systems, documentation is vital. Buyers should always request a hydrogen embrittlement fasteners PDF technical report. This file should verify the baking duration, temperature logs, and batch-specific testing results.
Eccentric Camber Adjustment Bolt for TOYOTA Suspension System | OEM
- Made from durable carbon steelfor high load-bearing performance
- Available in Grade 10.9 & 12.9 for enhanced strength
- Dacromet anti-corrosion finishensures long service life
Case Study: Solving Grade 10.9 Bolt Fractures
This case study examines a critical failure in high-strength automotive fasteners caused by hydrogen embrittlement.
Issue:
An automotive partner reported Grade 10.9 bolts snapping during torque application on an assembly line.
Problem:
Analysis of the hydrogen embrittlement fracture surface confirmed brittle intergranular failure. The factory found that the baking process started six hours after plating, exceeding the safe four-hour window.
Solution:
A strict “four-hour window” was enforced for all high-tensile components and increased baking time to eight hours.
Outcome:
The client reported zero fractures in subsequent batches, maintaining their production timeline.
Conclusion
Selecting the right hydrogen embrittlement-resistance fasteners is crucial. The wrong selection can lead to an abrupt failure with no warning signs. This failure can be catastrophic in safety-critical or load-bearing applications.
Hydrogen embrittlement and stress corrosion cracking can weaken high-strength fasteners over time. This may result in equipment damage, production loss, or injury.
Hydrogen embrittlement fasteners’ manufacturers must prioritize material science over high-volume shortcuts. It is also important to partner with manufacturers who truly understand embrittlement’s meaning, to prevent it from happening.
CNXD Auto maintains ISO 9001:2015 and IATF 16949 certifications. This ensures that our manufacturing processes meet the world’s most rigorous automotive standards. With a proven footprint in global exportation, we provide the technical transparency and material reliability required for modern engineering projects.
